1. Field of the Invention
The present invention relates to a magnetic recording/reproducing apparatus, and more particularly, to a reel apparatus for driving a tape cassette of a magnetic recording/reproducing apparatus.
2. Description of the Related Art
Generally, a magnetic recording/reproducing apparatus records information on a recording medium such as a magnetic tape, and also reproduces the recorded information from the recording medium. Examples of such magnetic recording/reproducing apparatuses mainly include video tape cassette recorders (VCR) and camcorders.
Referring to FIG. 1, a conventional magnetic recording/reproducing apparatus includes a main deck 2 on which a head drum 1 is rotatably mounted; a sub deck 3, which can be loaded/unloaded with respect to the main deck 2; a pair of reel assemblies 4, which are rotatable with respect to the sub deck 3 and drive the tape reel of the tape cassette; a reel assembly driving apparatus 7, which receives the driving force from a capstan motor 5 at the main deck 1 and selectively transmits the received driving force to the pair of reel assemblies 4; and a driving force transmitting unit 6, which transmits the driving force from the capstan motor 5 to the reel assembly driving apparatus 7.
The reel assemblies 4 include a supply part reel table (left-hand side of FIG. 1) to supply magnetic tape from the tape cassette, and a take-up part reel table (right-hand side of FIG. 1) to wind the magnetic tape as fed.
The driving force transmitting unit 6 includes a capstan gear 6a, driven in association with an axis gear 5a of the capstan motor 5, and a timing belt 6b, to transmit the driving force from the capstan gear 61a to the reel assembly driving apparatus 7.
The reel assembly driving apparatus 7 includes a pulley gear unit 7a, which is connected with a timing belt 6b, an idle gear 7b driven in association with the pulley gear unit 7a, and a pivoting plate 7c connecting the pulley gear unit 7a to the idle gear 7b. 
As shown in FIG. 2, the pivoting plate 7c may have an elastic part 7d which is cut in a predetermined pattern in the central portion of the pivoting plate 7c so as to function as a plate spring. Because the elastic part 7d is contacted with the idle gear 7b with a predetermined frictional force, when the idle gear 7b shifts the direction of its rotation, the pivoting plate 7c is subjected to a torque which causes the pivoting plate 7c to pivot. Accordingly, the idle gear 7b can be selectively connected to the left and right reel assemblies 4.
In the above-described construction, a part of rotational force of the pulley gear 11 is transmitted to a clutch gear 13 by the magnetic force generated between a magnet 12 and a metal piece 14. Since the rotational force can be reduced as the force is transmitted via the idle gear 7b to the destined reel assembly 4, the tape reel of the tape cassette can be rotated with the correct force.
However, in the conventional magnetic recording/reproducing apparatus constructed as above, because some components are required to provide a predetermined frictional force to the idle gear 7b to pivot the pivoting plate 7c, the overall construction becomes complicated. Further, as additional components are also required to control the torque to the tape cassette reel, the construction of the magnetic recording/reproducing apparatus becomes still more complicated. Also, because the price of the magnet employed in the conventional magnetic recording/reproducing apparatus is usually high, the manufacturing costs increase.
Alternatively, a frictional force generator, i.e., a torque generator as provided to the pulley gear unit 7a, can also be provided to the pair of reel assemblies 4 as a substitute. However, the problem is that this substitute also requires expensive components of rather complicated structure.